Fuel injection pump



Jan; 2, 1968, I J. G. CADIOU FUEL INJECTION PUMP Filed Oct. 21, 1965 United States Patent 3,361,075 FUEL INJECTION PUMP Jean G. Cadiou, Paris, France, assignor to Societe Anonyme Andre Citroen, Paris, France, a French society Filed Oct. 21, 1965, Ser. No. 499,360 Claims priority, application France, Apr. 16, 1965,

s 4 Claims. (at. 103-453) ABSTRACT OF THE DISCLOSURE The present invention relates to fuel injection pumps for feeding the cylinders of an internal combustion engrne, the pump being composed essentially of a cylinder having a single aperture serving both for inlet and discharge of the fuel, a piston, and a lever pivotally mounted at its centre. The latter has a first arm which drives, by its end, the piston into the cylinder during the discharge stroke and a second arm whose end is pushed back by the apex of a cam.

It is an object of the invention to provide a fuel injection pump of this kind which shall operate more efiiciently.

In the pump according to the invention, the piston is returned by the first arm of the lever during the inlet stroke and the play or clearance between these two parts is taken up by means of a bent or curved spring, one end of which is secured to or integral with the end of the first arm of said lever and the other end of which is secured to the piston. The spring preferably comprises two wires disposed symmetrically on either side of the first arm and the piston.

The return of the second arm of the lever against the surface of the cam during the inlet stroke and the taking up of the clearance between these two parts are effected by a hairpin spring, the end of one limb of which passes around half the circumference of the pivot axis of the lever, and is secured to this lever, the end of the other limb being mounted to slide in a rotary joint, itself mounted to oscillate in a corresponding housing in the casing. The spring may be composed of a plurality of wires disposed side by side or on either side of the second arm of the lever.

In order that the invention may be more readily understood, reference will now be made to the accompanying drawing which shows one embodiment thereof by way of example, which drawing is a transverse section through a fuel injection pump provided with return springs according to the invention. The following description will be limited to the designation of the essential parts necessary for understanding the invention.

Referring to the drawing, there is shown a pump with a cylinder 1 that has a single aperture 2 which serves for the inlet and discharge of fuel into and out of a chamber 3 defined between the cylinder 1 and a piston 4. The outer end of the latter is bored at 5, and in this bore there engages a pin 6, which projects away from the bore 5. The other end 6a of the pin 6 extends into an orifice 7 located at the end of a first arm 8a of a lever 8. The latter is pivotally mounted at its centre about a spindle or shaft 9 and its second arm 85 is provided with a roller 10 which is supported on the surface of a cam 11 rotatable in the direction of the arrow F at a suitable speed.

As is known, the cam 11, by each of its apices or crowns (4 in this example), causes the piston 4 to be driven into the cylinder 1 by means of the lever 8 at the moment of the fuel discharge phase and its injection into the cylinder. Then the fuel is admitted into the chamber 3 while the piston 5 and the first arm 8a are being lifted again and the second arm 8b is being lowered.

The piston 4 is returned when the arm 8a rises up and the play between the piston 4, the needle 6 and the arm 8 is permanently taken up by means of a spring 12. The latter, constituted by a fiat wire bent or curved at its centre, has a first limb 1211 which is fixed at its end to the end of the arm 8a. The second limb 12b of the spring 12 has a loop, which is not entirely closed, which passes over a peg 13 secured to the upper end of the piston 4. This method of fixing the spring 12 to the piston 4 allows the spring to be rapidly mounted and removed, but various modifications could be made to these details, if desired.

Of course, in order to balance the forces exerted on the piston 4, two springs such as 12 can be placed symmetrically on either side of the arm 8a.

The holding of the arm 8b against the surface of the cam 11 and the permanent taking up of the play between the roller 10 and the cam 11 are effected by means of a spring 14. The latter has a semi-circular limb 14a which partially surrounds the essential parts of the lever 8 and the spindle or shaft 9 and which is fixed at its end through a catch of the lever 8. The end of the other limb 14b of the spring 14 passes into a bore 15a of a rotary (ball-and-socket) joint 15 where it is able to slide. The joint 15 is itself mounted to oscillate in a suitable housing 16 in the casing of the assembly of the fuel injection device.

The spring 14 may be composed of a plurality of identical wires disposed parallel to one another. The spring 14 ensures that all the movable parts are returned without introducing abnormal forces due to the particular articulations of the end of its limb 14b.

It will be observed that the assembly of the pump is disposed in planes perpendicular to the drive shaft and has a generally fiat form, which is less cumbersome in the axial direction of the shaft. The ends of the latter are free and are easily accessible, one may co-operate with rotation means and the other may serve to control another member, as for example fuel distributing means.

The invention covers all the different modifications or variants of detail which could be given to the assembly shown without departing either from the scope or the spirit of the invention as defined by the appended claims.

I claim:

1. A fuel injection pump comprising a cylinder, a single inlet and discharge aperture adjacent to one end of said cylinder, a piston within said cylinder, a twoarmed lever pivotally mounted at its center, a spring connected between one arm of said lever and said piston, a rotary cam operable to oscillate the other arm of said lever and reciprocate said piston through said spring.

2. The fuel injection pump defined in claim 1 further comprising a bore in said piston, an orifice in said one arm, and a pin, one end of said pin being disposed in said bore and the other arm of said pin being disposed in said orifice whereby when said one arm moves toward said piston said spring is contracted and said pin is driven to the end of said bore to drive said piston toward said aperture.

3. The fuel injection pump defined in claim 2 wherein r. CC

said spring is generally C-shaped and secured at one end to said lever and at the other end to said piston.

4. The fuel injection pump defined in claim 3 further comprising a roller rotatably mounted on said other arm and engaging at its periphery said cam, a pump casing, a socket in said casing, a ball in said socket, a second spring having two limbs and extending substantially halfway around the pivot of said lever, one of said limbs secured to said lever and the other of said limbs extending into said ball, whereby said second spring urges said other arm toward said cam to assure that said roller always contacts said cam and said ball and socket permit said second spring to flex freely during said oscillation of said lever toward said cam to assure that said roller is always in contact with said cam.

References Cited UNITED STATES PATENTS 1,280,511 10/1918 Macbeth 230-119 1,717,365 6/1929 Bremer 103153 2,100,972 11/1937 Michaels 230217 2,257,387 9/1941 Kinrade et a1. 103-153 2,510,003 5/1950 Wieseltier 103-211 3,291,350 12/1966 Malec 103-153 HENRY F. RADUAZO, Primary Examiner. 

